Astros general manager Jeff Luhnow backed up Porter, saying the club could either use a sixth starter or standard reliever in extended relief.

The Astros’ move to the American League played a role in the decision.

“If your starter doesn’t last two innings, you need to make up for it without killing your bullpen,” Luhnow said.

Stepping back

Non-roster invitee Max Stassi continues to deal with an oblique injury that has limited his activity since training camp began.

The Astros believe the 21-year-old catcher could have a sports hernia that’s triggering his oblique strain. Stassi thinks a previous ankle injury could also be related to the hernia.

Stassi plans to travel to Philadelphia next week to be evaluated by a specialist. Surgery is a possibility, and an official timetable for his return won’t be set until after Stassi is seen by a doctor. The catcher is likely to miss the majority of spring training, though, and hopes to be cleared by the start of the regular season.

Stassi has played through multiple injuries the last 18 months. After being acquired by the Astros in the recent Jed Lowrie deal, the catcher is seeking a second opinion so he can focus on his long-term health.

“If it’s weak in the hip or the front, then something has to compensate, which is my oblique,” Stassi said. “My hip region has been bothering me for a year and a half and I’ve just played through it.”

Rough debut

Jose Veras was off target in the third inning Sunday.

The regular season Astros closer allowed a two-run homer to Jordany Valdespin and failed to retire the first three Mets batters he faced. Veras’ final line (1 IP, 2 ER, 1 BB, 1 H) looks rough and he plunked the Mets’ Josh Satin with his first pitch. But Veras’ three outs came via strikeouts and he threw a breaking ball-heavy frame.

“Early on he kind of missed his spot a couple of times. The fastball that was hit out of the ballpark was a little bit elevated,” Porter said. “Again, this is his first time out. At the same time, he did a good job of battling through the situation and making it through the inning.”

Better start

Astros catcher Jason Castro homered to right field in the fourth inning, connecting on a Jeremy Hefner 3-1 pitch that drove in George Springer.

After struggling with injuries in 2012 and being limited to 87 games, the 25-year-old Castro is healthy this season and quickly becoming one of the Astros’ clubhouse and on-the-field leaders.

“We’re all starting to see the Castro we believed we were getting when we drafted him,” Porter said.

Quick hits: Prospect Nate Frieman went 2 for 2 Sunday and has started spring training 3 for 5. … The Astros have recorded six stolen bases and 24 hits in two games.

Notes

Porter is more concerned about getting at-bats for first basemen Brett Wallace, Chris Carter, Carlos Pena and Freiman than which position they play early during spring training. Pena played first Sunday while Wallace was the Astros’ designated hitter. Wallace is scheduled to play third Monday against St. Louis, with Carter at first. … Porter said the Astros will often use defensive shifts against power hitters who regularly pull the ball. The Astros heavily adjusted their defense Saturday against Philadelphia slugger Ryan Howard. … Right-hander Philip Humber will start Monday for the Astros against St. Louis in Jupiter, Fla. Righty Adam Wainwright is set to start for the Cardinals.